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Batteries, the Achilles Heel

The sale of EVs and PHEVs has been sluggish, probably because of the high cost of the battery. The 16 kWh battery for the Volt, for example, costs around $10,000, while the 24 kWh battery for the Leaf costs around $15,000.

From the buyer’s perspective, the savings from not using gasoline is an important economic factor in the buying decision.

For the Volt, assuming the vehicle is only used for commuting less than 25 miles, it might be possible to travel the usual 12,000 miles per year without using gasoline. At $4 per gallon, and, assuming 35 mpg for comparable ICE vehicles, the buyer would save approximately $1,400 per year.

The buyer could, in this instance, recover the extra cost for the Volt battery in slightly over 7 years.

If, the Volt is used for longer drives, where it uses gasoline for half the miles driven, or 6,000 miles, it would take over 14 years to recover the added cost of the battery.

The cost of the battery for the all electric Leaf is around $15,000, and it would require roughly 11 years to recover its added cost.

In both instances, estimated battery life is around 8 to 10 years, so that, in most instances, the buyer will never recover the added cost of the battery.

What would it take to cut recovery periods to four years, the length of time many buyers plan on keeping a new vehicle?

With savings of $1,400 per year, it would require that the battery for the Volt and the Leaf cost around $5,500; or roughly half the cost of the current Volt battery and one-third the cost of the current Leaf battery. – Remember also, that the Leaf can only travel 100 miles on this size battery.

But, is cutting the cost of the battery to $5,500 realistic?

There is considerable hype in the media on this question, so here is some information that may help you decide.

Li-ion Cost and Energy Density Curve

It’s evident from this graph that energy density, Wh/kg, in green, is plateauing, while the cost curve, blue, is asymptotic, or leveling off, indicating that cost improvements are likely to be minuscule. To arrive at total battery cost, it’s necessary to add the cost of packaging, which is currently around $300 kWh, to the cost of Li-ion cells.

To cut the cost of the Volt battery in half, requires either cutting the cell cost, $/Wh, or doubling the energy density, while achieving comparable reductions in packaging costs.

Focusing on cells, it means increasing energy density from 202 Wh/kg, to over 400 Wh/kg for the Volt. For the Leaf, it means tripling the energy density to over 600 Wh/kg.

Even if the Leaf can achieve this objective, it wouldn’t increase its range beyond 100 miles.

The Argonne National Laboratory has proposed theoretical solutions to the problem, including entirely different battery chemistries. Even DOE, in its 2011 presentation1, categorizes these solutions as high risk. The Argonne Lab’s high risk proposals don’t double energy density until, possibly, 2030, while not even proposing to triple energy density in this time frame.

A glance at the accompanying chart demonstrates that it’s not possible to achieve the required lower battery costs without revolutionary breakthroughs.

“There are no commercially available high energy materials that can produce a battery capable of meeting the 40-mile all-electric-range (AER) within the weight and volume constraints established for PHEVs by DOE and the USABC.2”

It’s worth keeping in mind that there has been tremendous interest in batteries for at least the past 20 years – actually for at least 30 years when GE had a battery business in Gainesville, Florida, and GE’s scientists decided the obstacles were too great to consider growing the business in anticipation of the automotive market.

The current Li-ion batteries, with six times the energy density of lead-acid batteries, are the only big automotive battery breakthrough in the past 25 years.

It’s also worth recognizing that the consumer products industry has built millions of Li-ion batteries while attempting to cut costs.

With this prior concentration of effort, one could assume that major breakthroughs are going to be very difficult to achieve.

Prospects for cutting battery costs are not good.

Whatever conclusions individuals reach, it will affect their buying decisions, and also how they feel about using tax-payer money for subsidies and investments.

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It seems to me that cost-feasible electricity storage is not simply a game-changer for the entire energy market, but history altering. Just one example: My 10KW solar array supplies all the power I need each month in 5 days or less. The rest feeds into the grid, basically making the grid a big battery for me.

But I pay $.13/KWH to draw power at night and only get paid $.08/KWH for my excess. Imagine if I could cheaply store and consume all of my excess, and note that solar panels are now being projected to fall to $.42/KWH by 2015, inching us closer to $1/watt for Solar PV at the residential level. That would translate into a sub-10 year payback on a 30-year system. Tens of millions would jump on it, without subsidies. And self-consumption would also ameliorate the grid-accommodation claims utilities and grid operators now make.

I would be indebted to you if you would post any new research you find on cost-feasible electricity storage, as you obviously are dialed into the energy sector.

James:
Sorry, but I don’t have any more information than you probably have. As you know, there are a few experiments with house-sized batteries, and, of course, the only proven method for storing large amounts of electricity is with pumped storage … and that’s a problem in terms of location, cost and objections from environmentalists.

Thanks. I’ll look forward to any information you may find.
Regarding the link in your comment.
It’s an example of a little information being dangerous.
The hypothesis the individual describes is highly unlikely and can only come about if tax payer money is used to foster the development of roof-top solar energy. Even then, the hypothesis requires that sufficient storage is available to cover night time and cloudy days.
The one aspect of the article in question that’s accurate, is that the people using roof-top solar, for which they, in most cases, derive a subsidy, either directly or indirectly, forces their neighbors, who don’t have solar, to pay for the transmission and distribution lines, and the back-up power that assures high reliability, for which the solar home doesn’t pay.
Using roof top solar, without any subsidy or reimbursement for the excess power that’s produced, may be beneficial in unique circumstances, such as farms or cabins in remote areas, but as a replacement for utility generated, low-cost, reliable electricity, it’s bad for America.
Utilities are obviously aware of the problem, and PG&E, for one, has pointed out the dangers.